1. Field of the Invention
The invention relates to line blinds, and, in particular, to sliding gate line blinds. More particularly, the present invention is related to sliding gate line blind valves.
2. Description of the Related Art
Sliding gate line blinds for preventing leakage of the contents of a pipeline are well known in the art.
U.S. Pat. No. 4,489,918 discloses a non-floating seat for expanding gate valves. To prevent pressure induced floating of the interference fitted seats of expanding gate valves, a seat ring body is provided which is press fitted within the upstream seat recess of a valve body. The seat ring body defines a sealing face of circular form which is disposed for sealing engagement with the segment portion of an expanding gate and segment assembly. The seat ring body also defines an axial extension tube extending upstream from the seat ring body with a circular sealing lip defining the outer periphery thereof being in radial sealing engagement with a reduced diameter portion of the seat recess. The radial extension is pressure yieldable to enhance the radial sealing capability thereof and defines a pressure responsive area that is equal to or less than the pressure responsive area of the sealing face.
U.S. Pat. No. 4,487,393 discloses a gate valve having a pressure-secured seat. The valve includes a valve body having a cavity formed therein and an inlet and outlet formed in the body, both of which intersect the cavity. A counterbore is formed about the circumference of both the inlet and the outlet at their respective intersections with the cavity. An annular seat having a rear surface and a front seat surface is received within the inlet counterbore. An annular seal is formed on the front seat surface and a second annular seal is disposed between the rear surface and the valve body. The front annular seal has a sealing diameter greater than the rear annular seal and an annular recess is formed on the front seat surface on the radially inward side of the annular seal. A second annular seat having a planar front seat surface is received within the outlet counterbore. An expandable gate is mounted for selective vertical positioning in the cavity for permitting flow between the inlet and outlet in one position and for sealing off such flow in another position. When in position for sealing off such flow, the gate is expanded into sealing engagement with the first and second seats.
U.S. Pat. No. 3,923,285 discloses a stem connection for gate valves including a pair of split connector sections which fit over adjacent enlarged end portions of the gate element and stem. The connector sections receive the enlarged end portions in a cavity and a cap fits over the split sections to hold the sections about the enlarged end portions of the gate element and stem. The cap and split sections are rapidly disassembled and reassembled about the enlarged end portions.
U.S. Pat. No. 3,068,901 discloses a three way gate valve including a housing having an open ended internal valve chamber, a detachable bonnet closing the open ended chamber, an inlet port communicating with the chamber, a first outlet port communicating with the chamber, the first outlet port being axially aligned with but diametrically opposed to the inlet port, a second outlet port communicating with the chamber, an annular pocket surrounding the inlet port and first outlet port, one side of each pocket being open to its respective part and another side open to the chamber, a valve seat member located in each of the pockets, a reciprocating two piece parallel expanding type valve member located in the chamber, the valve member having generally parallel sealing faces opposing the seat members and abutting angular faces whereby the valve member can parallelly expand, the valve member having a through passage alignable with the inlet port and first outlet port and a second passage connectable with the inlet port and the second outlet port, the valve member and seat members being so constructed that when the through passage of the valve member is aligned with the inlet port and the first outlet port that the valve member expands to establish seals with the seats from either side and the abutting angular faces contact each other in sealing relationship, a stem extending from the valve member through the bonnet, a device to move the valve member from one position to another.
U.S. Pat. No. 3,060,964 discloses a valve having vented housing including a fluid conduit having a wall with an aperture device therein; a valve seat device in the conduit; a closure device coacting with the valve seat device to open and close the conduit, the closure device extending through the aperture device to the outside of the conduit; a hollow housing on the outside of the conduit enclosing the closure device and the aperture device; a bonnet on the top of the housing; the construction and arrangement being such that fluid may accumulate in the housing while the valve is open and fluid flows through the passage, and that fluid normally is trapped in the housing when the valve is closed thereafter, including two bores through the wall of the conduit on opposite sides of the valve seat device and located within the circumference of the housing, two individual tubes secured in the bores and projecting into the upper portion of the housing beneath the bonnet, the tubes establishing communication between the inside of the conduit and the inside of the housing, and two normally closed independent check valves on the upper ends of and controlling the tubes, the check valves acting to open when the pressure inside the housing exceeds the pressure in the conduit adjacent the respective bores to release fluid to the conduit.
U.S. Pat. No. 2,478,811 discloses a power-operated gate valve of "through conduit" gate type with a fluid pressure device for operating the valve to its open and closed positions, including a pair of double-tapered sliding gate elements that are displaceable in a direction normal to that of their sliding movement by relative endwise movement in order to effect sealing engagement with the valve seats in both the open and closed positions of the valve, a valve housing which completely encloses the valve and its operating device, the operating device including opposed fluid operating pistons in opposite ends of the housing with the gate elements interposed therebetween and with the opposite ends of the gate elements providing abutments to be engaged by the pistons to operate the valve, a lost motion device interconnecting the opposed pistons, and fixed abutments within the housing to limit the sliding movement of one of the gate elements at the opposite ends of the one gate element, the companion element is movable relative thereto in order to laterally displace the two gate elements to effect sealing engagement of both the elements with the valve seats at both ends of the valve travel.